I don't think the current Lemmy clients allow hiding bots, but if they really bother you/people that much, it should possible to add options to hide bots altogether.
I currently host the official instance, which is entirely run by donations. However, there are many community instances people can switch to in the preferences menu on the site. They are listed at https://github.com/TeamPiped/Piped/wiki/Instances
You can just change the hostname, for example,
youtube.com
topiped.video
. Alternatively, you could just use something like Libredirect to automatically do it on your browser.