I'm sure you know where to find this, right?
FCL.940.FI FI – Revalidation and renewal Regulation (EU) 2020/359
(a) Revalidation
(1) To revalidate an FI certificate, holders shall fulfil at least two out of the three following
requirements before the expiry date of the FI certificate:
(i) they have completed:
(A) in the case of an FI(A) and an FI(H), at least 50 hours of flight instruction in
the appropriate aircraft category as FIs, TRIs, CRIs, IRIs, MIs or examiners. If
the privileges to instruct for the IR are to be revalidated, at least 10 of those
hours shall be flight instruction for an IR and shall have been completed in
the period of 12 months immediately preceding the expiry date of the FI
certificate;
"The appropriate aircraft category" means SEP as far as I know, so not a microlight unless it is a type that can be flown under EASA CS-23 rules. Yet a while ago the rules were updated to allow Microlight aircraft hours to count for your recency requirements to revalidate your SEP, but whether this applies to instructing hours as well... that's a question that I cannot answer. Perhaps
BEagle or
Whopity knows?