It is upside in the way of, these taxes are necessary to bring up the economic status of one's country once again.
If this implementation can help the economy to recover I think its not going to be a big deal because it has a purpose. Besides online casinos gain more players in the past months that we are in lockdown because they are looking for an alternative to still gamble and satisfy themselves.
On the other hand, it is downside simply because users must now have to compromise with this situation. Besides, having a regulation will now break the form of anonymity on online gambling.
I think it depends on casinos because we can still have an option. The sad part is gamblers might be affected of this taxation, win or lose you have a contribution.