I’ve gotten free trial offers for Nitro a couple of times, and it seems to be fairly random.
The last time I got one was about six months ago, and it was the same, only visible on PC.
I’ve heard that Discord rolls out free trials periodically, but it’s often linked to certain account activity or promotions.
Honestly, I wouldn’t expect them to be too frequent unless you’re actively using Discord for streaming or server boosting. It’s nice to get the offer, though—definitely makes the perks feel a little more accessible!