Interestingly, Amazon has the manga of this series on Kindle Unlimited now, as "The Thunder Magican (sic) returns to be the strongest: Reincarnation", and priced at US$3 per book.

It's suspicious because it has the publisher as "Cherepanova It", all 4 volumes show the same cover (but different page counts), all were released on 8/31/2021, and the page order is left-to-right, instead of right-to-left.

There is another "volume 2" that is "under review", by Adam Thibodeau.

I expect that, once Amazon reviews the submission, I'll get a $12 refund and the books will disappear.

Edited to add: oh, what a surprise! It's a scanlation, complete with the translator's notes about caring for his sick mother...