If you would like to get it replaced...
... I believe Apple will do it for you, IF the battery health has dropped below 80% (yours has).
It's not exactly "cheap" @$249, but then again, not all that expensive either.
You get an Apple-labeled battery, installation, and a short warranty.
If it was me, I'd keep using it "as it is" for a little while longer, but get the replacement before the end of 2026...