Edit:
I'm not sure what the problem is with ebay.
The money back guarantee is still valid even if covid is used as an excuse.
I've had a few things not arrive in the last year and
always got
all of my money back.
If it doesn't arrive within say 3-5 days after last estimated arrival date then contact the seller directly... use ask question, other or whatever but don't put in a did not receive ticket immediately.
You ask about it first and then move onto putting a claim into the system if you can't resolve the issue with the seller within 24-48 hours.
Always stay civil.
It's pretty simple really
You'd be surprised how many people think that angry messages and the like are justified, even swearing, if something doesn't arrive or other issues (wrong item etc).
But it doesn't do anything positive for your case if it's looked over.