In my corner of the world this appears to be more common or just tolerated more since most of the IT workers are, for lack of a better word, pretend contractors

In my corner of the world this appears to be more common or just tolerated more since most of the IT workers are, for lack of a better word, pretend contractors(for tax reasons), so companies can't impose certain restrictions or else the tax authority will recognize this relationship as employment and demand taxes and social security payments retroactively. Since late 2019 each contract of mine started including a clause stating that I should prioritize this particular client. That is the extent to which they went to date with restrictions. I'm also required to notify them of any other client that I might have. Apparently they're keeping an eye on the overemployed. In any case most people in my team had some kind of side gig, or had this project as the side gig and we decided to be open about it. I know people who have been pulling 2-3 contracts for years now. That being said the most overemployed is already experiencing heart issues in his 30s, so he might have to back down soon. I both have a small child and am too chicken to actually try it, but to be completely honest large organisations have such narrow roles and move at such a slow pace that it's not difficult to meet expectations while having two "full time"(heavy quotes here) contracts. Personally I use this slack to spend more time with my family. My salary overtook my lifestyle expectations in 2019 so finances are not a problem.