Uh, no. Having anything like that pinned to an intermediate doesn't make any sense. The intermediates can, will, and do change regularly. Sometimes, as in this case, with plenty of notice. But Let's Encrypt also keeps intermediates in reserve for disaster recovery, so they might have switched to R4 at any point in the past few years without any further notice.
If you have the certificate and private key from before your most recent renewal, you might be able to roll back to that to use it temporarily if it's not yet expired.