Like many have asked before (for different reasons) for years (even before we had this suggestions platform) and as you can see with other suggestions in this platform too:
There is a need by some people to be able to avoid private messages for non-contacts.
Why?: There are many reasons on why to add this feature.
As a social person i enjoy being inside Public Groups. It's amazing to be able to talk to other people from all around the world.
But it comes with a cost:
Users/Scammers/Spammers and Autommated Accouns that are (or not) inside public groups can annoy you in private.
For some unclear reason Telegram decided to just ignore the issue. They added a bunch of options that are not enough.
For example there is a hidden privacy option to Archive and Silence new Private Messages from non-contact users.
It's a step forward but this option only appears if you litterally get bombarded with hundreds of unknown users...
Most of the people that ask for a way to disable Private Messages from non-contacts are females.
Making that option hidden until some unknown conditional is reached feels like Telegram is embracing all those Creeps to allow them to annoy those females in private.
Not letting anyone decide if they want to (or not) receive private messages just kills the spirit of Public Groups for some minorities.
To be fair: We already asked and made noise with this topic back in 2016 or 2017... Probably no one will give a f*** about this.
Telegram Team lives in a bubble for years, they see things from another prespective as a New User that starts with Telegram, enters it's first masive Public Group and then it gets countless messages from bad people.
And don't take me wrong... More than 80% of people are really nice human beings... But in a group of 10K users even if just the 10% are the worst it's enough to drive you crazy with private messages from strangers.