Is it legal to ask the employee to resign while on vacation?

Dear Sir,

I am a UAE resident and I work in a Dubi based company in Deira Dubai. I went on vacation on the 1st of March and supposed to come back to Dubai on 25th of March.

Due to COVID-19 travel restrictions, my company asked me to stay in my home country up to 30th June on unpaid leave. Today my manager called me and asked me to send a resignation letter.

I wanted to share with you that I was a good performer in my company and was achieving my targets. Is it legal to ask a resignation while I am on leave and they did not initiate termination but asking me to resign?

Please also advise, is the company responsible to pay me full gratuity? And if the company terminates me, then am I also eligible to get 3 months salary as compensation?

Please help me to cope with this situation.

Thanks and regards,

A. Z.