Net core can run applications on windows and linux with a short configurations . Please add support to both OS

Add a setting to disable mail forwarding to certain domains in Panel for global configuration so that on user side wont be allowed to put the certain domains in the Forwarding Email in the Plesk Panel. Thank you.

https://support.plesk.com/hc/en-us/articles/213410369-How-to-perform-dist-upgrade-procedure-on-Linux-server-with-Plesk-

At this moment you can change favicon.ico by replacing /usr/local/psa/admin/htdocs/favicon.ico, however it will be replaced on Plesk update.

It is also not possible to make it permanent using custom theme from Plesk branding guide.

Please make a way to customize favicon.ico on permanent basis

Add Redis support for Plesk for Linux so we can manage it directly via Plesk GUI

Free version of Enterprise Litespeed, it would be nice to use lsphp+Openlitespeed+LSCache (free) within Plesk.

Add mail autodiscover functionality for iOS/OS & android mail clients please.

An option to customize outgoing SMTP port.
Both for SMTP relay and direct SMTP.
Currently there's only a temporary workaround for Google Cloud VMs with Plesk.
This configuration might be overwritten by an update:
https://support.plesk.com/hc/en-us/articles/115004060494

example.com doesn't exist on the server.

If set example.com under Plesk > Tools & Settings > Customize Plesk URL, there is no redirect from http://example.com to https://example.com.

Please add feature - redirect from HTTP to HTTPS to access Plesk login page.

Add the possibility to prevent/block any file or directory removal from within the File Manager in Plesk by the subscription/domain users.

An example that could be applied is the same as it can be applied already for ProFTP config files as follows:

<Directory /var/www/vhosts/*/.cagefs>
<Limit ALL>
DenyAll
</Limit>
</Directory>

<Directory /var/www/vhosts/*/.cl.selector>
<Limit ALL>
DenyAll
</Limit>
</Directory>

<Directory /var/www/vhosts/*/error_docs>
<Limit DELE>
DenyAll
</Limit>
</Directory>

<Directory /var/www/vhosts/*/httpdocs>
<Limit RMD>
DenyAll
</Limit>
</Directory>

<Directory /var/www/vhosts//httpdocs/>
<Limit RMD>
AllowAll
</Limit>
</Directory>

Would be good to be able to manage SMTPUFT8 option over Plesk so that it is not reverted after Plesk Updates and also to remove the need to manage this option over the Postfix config directly.

More information:
https://talk.plesk.com/threads/smtputf8-is-required-but-was-not-offered-by-host.351377/
http://www.postfix.org/SMTPUTF8_README.html

This idea was already mentioned on: https://plesk.uservoice.com/forums/184549-feature-suggestions/suggestions/39722035-custom-labels-in-wp-toolkit-and-additional-filteri

And to give some ideas of what custom labels could be added:
- managed / unmanaged
- notes about who manages the site
- notes about special environments besides production / staging / ...

It would be less work to not have to look up these informations for each site and be able to just add a short custom label. For us these labels do not need to be filtered, but it would be a nice-to-have to have this addition like described in the original thread.

By default Docker container is available from the outside and Plesk users sometimes are unaware of it. Sometimes Docker container is used only locally.
Suggestion is to add a warning about this or add a check box to close remote access on creation.

Calculate backup files created by administrator not server-wide, but per specific subscriptions.

According to Postfix documentation, multiple Postfix instances are supported. Would like to have such support implemented in Plesk
http://www.postfix.org/MULTIINSTANCEREADME.html

Currently Plesk administrator is able to see active FTP sessions in Plesk interface. It would be nice monitoring feature to add if the same could be done with active SFTP sessions.

Currently Plesk has not remove the domain from the remote SmarterMail server and just disabled the it due to business logic (When a subscription is suspended, mail service and hosting service will be temporarily stopped to avoid losing mail data)

Add possibility remove domain from remote SmarterMail, when mail service disabled by administrator manually

In Windows Server IIS, it is recommended to set loadUserProfile:true for dedicated application pools. Doing so guarantees better application isolation and security for web applications created with ASP.NET, .NET Core or PHP.

You can find some basic information about this setting in this Stack Overflow answer: https://stackoverflow.com/a/17149834/1297898.
Official Microsoft documentation: https://docs.microsoft.com/en-us/iis/manage/configuring-security/application-pool-identities, https://docs.microsoft.com/en-us/iis/manage/configuring-security/ensure-security-isolation-for-web-sites

I will be pleased to provide any additional information you may require.