Interesting, I didn’t know that turning off DNSSEC before transfer was required! I transferred my domain from googledomains to Cloudflare, which is now the new registrar. I can no longer access the domain at google and don’t remember if it had DNSSEC enabled. May I ask how you concluded that DNSSEC was enabled before at your domain?
I used https://dnsviz.net to check my domain and it’s clearly broken. The top graph shows DNSKEY with Algorithm 8 and at the bottom in red it shows DNSKEY with Algorithm 13, which I understand is what Cloudflare uses, so that graph now makes more sense thanks to your question, as it could be a clue that indeed DNSSEC was enabled before.
When I use dig on mydomain I get SERVFAIL and “no SEP matching the DS found for mydomain”. Also, on the Cloudflare DNS settings, I’ve clicked the “Enable DNSSEC” button and it still says “DNSSEC is pending while we automatically add the DS record on your domain.”. Several days have passed in this state. I don’t think I can open a ticket on a free plan, so would appreciate any solution. Thank you!