First, for the collectibles Yahoo account, go into Settings >> Accounts >> Outgoing >> set the port to 465, Security Type to SSL >> Save.
Then, for your other main Yahoo, logon here
https://login.yahoo.com/myaccount/security/ and select to generate an App Password >> with this new gibberish password, enter that into MailWasher under Settings >> Accounts >> Incoming >> and also under Advanced uncheck the option to Use OAUTH >> Save. That should still check the account fine.
That said, while it will fix the errors I can see in the log. I don't believe it will work for you as it does seem Yahoo is filtering these bounces. I've tried several addresses on my test Yahoo account and none of them have received anything.
What I would look at next, is if you visit the Yahoo mail page
https://mail.yahoo.com/ for the account, you can check the messages and hit the SPAM button, there is the option to Unsubscribe, which I think might stop them from arriving in future, but also the Report Spam option.
I don't know about Yahoo specifically, but other email providers have been known to start blocking all emails from these services if enough people report them as spam. I know this, as we sometimes get blocked as people report our newsletters as spam rather than unsubscribe
It's worth a shot given just how much of these you do seem to be receiving.
Other options, you could blacklist these addresses and then set your Blacklist to auto-delete (Settings >> Spam Tools >> Blacklist >> Options). They will then delete when MailWasher checks for messages, so they won't appear on your screen at all.
If you don't want to auto-delete all blacklisted addresses, then a Custom Filter that looks at the FROM FIELD, CONTAINS, PLAIN TEXT, emailaddress....
When you have several addresses you want removed, set the filter to match ANY rule not ALL, and do one email address per rule within the filter.
Once the filter is working and tagging the emails you expect it to, under the Options tab for that specific filter, you can also set to auto-delete.
Hope this helps in some way, is not ideal.
Cheers