Until now Celcom and its MVNOs including Unifi Mobile Bebas Prepaid remains unaffected by this implementation of new 5G restrictions yet. But *touchwood it's a matter of time they'll since telcos in Malaysia are notoriously sly and nasty. You see recently how many news some of their top management involved in scandals as such and you see the very same faces hopping around from one company to another.
All the higher tiered wireless 4G plans which costs more than monthly fibre plans (RM89) above range is still unaffected.

For those who are subscribing to Maxis 4G Home WiFi or their Maxis One Plan with Fibre Plan attached you're already paying more than RM150 per month. That is why they're not disturbing these high value customers.
Celcom and all its MVNOs remain unaffected till now but don't be too confident just yet they might soon join the bad side if the public still remain unaware of the dirty new tactic they started pulling.
The latest Hotlink plan says Unlimited Hotspot including Data and Calls.

If I place the SIM in the phone and turn on hotspot sharing or place it in a dedicated modem what difference does it makes? Aren't we all already subjected to a 50GB FUP? Not enough?

It's misleading and very dishonest to their customers. 
Dare telling us which modem you're using? It won't be long once they finds out your modem IMEI and MAC ID will be put on blacklist and deprioritized by YES. Later don't cry ya and go complainning to YES. They'll just give you standard script reply saying your device is "NOT" in their supported device list. Thanks to 5G new network features.