WG is not meant to be a stealthy protocol and is easy to detect at the ISP level. It has distinct characteristics that packet inspection tools can use to identify it by examining the traffic and block or flag it. Blocking it completely is trivial for any ISP, much less a nation.

There are modified versions like AmneziaWG that make it stealthier, or alternative protocols built to evade traffic inspection like xray or sing-box (these two are really more like protocol frameworks that have multiple protocols you can use). It’s a bit of an arms race for packet inspection tools to be able to reliably identify these intentionally stealthy protocols, but the advantage is generally in your favor as long as you are using your own servers and not public VPNs. Though even then you need to take care to camouflage your traffic to be truly safe, like if you are shoving all of your traffic through one remote server that has approximately the same amount of traffic going out immediately etc that is something that can also be identified.

How much precaution is actually warranted depends on where you are and what the potential consequences are. You don’t have to go to a full tinfoil hat paranoia level setup to avoid most blocking.