Unlimited or 50gb data (at relatively low cost) is probably discontinued.

2G was discontinued for the whole SG due to regulation.

iirc there was an unlimited mobile Internet plan for $10+ years ago, which got grandfathered (means existing plan holders keep it indefinitely) when the plan discontinued. I was feeling a little bummed for not having signed up. Just as well, since it was a good deal then, but probably not necessarily a good deal now.

I wonder if telcos actually store when the corporate plan holders' employment contract ends. There's a fair chance they don't.

In a pinch you can get StarHub's prepaid sim, and use their overseas data plan (possibly enough data for messenging app (if you disable auto-download of images and videos), maps, research. But not for YouTube watching.)

Just don't accidentally trigger roaming data for your postpaid, because the costs are crazy, and typically they don't waive it all even for accidental first times.