The last time that YouTube used Flash Player, was in 2015. That is about 8 years ago, nearly a decade. I’ve installed Linux Mint on devices by relatives and they have not really had any major issues since, the first instance of that was 2 years ago.
Since 2015, which seems to me was the last time you tried a Linux Distribution, things have changed dramatically. About 5 years ago, Valve released their first version of Proton - a compatibility layer for windows programs based on Wine, DXVK and other tooling - that has been able to run tons of programs up to this point and has only been improving. In the games department alone about 87% of the top 1000 games have been marked as playable by the community. In terms of other software there’s been a massive shift from trying to run Windows Software to instead looking for alternatives and/or programs which fill your needs, as you should when switching operating systems. After all, when someone switches to macOS from Windows or vice versa, they wouldn’t expect to have the same Windows-Only software, or macOS-Only software.
Last year, the Steam Deck released, which ships with a full, user-facing version of Linux developed in-house by Valve called SteamOS. That marked the moment where another, decently sized development team working on various different aspects of the Linux desktop stack was being paid to continue developing to ensure a better experience, and Valve is known for upstreaming their fixes and changes where possible, contributing back to the experience for the benefit of everyone.
I don’t know when you’ve last tried Linux on the desktop, but in case it really hasn’t been since 2015 I encourage you to give it another try. Things have changed, and whilst - like any software - the experience still isn’t perfect, it has come a long way from the experience you’re describing, even when comparing it to a shorter timespan like from 2019 to now.