In principle it is bicycle only. The round blue sign with the bicycle in it makes it a bicycle path where cars are not allowed. Certain mopeds (ones that go less than 30km/h) are normally allowed, but the sign under the round one bans them as well.

Maybe some car traffic is allowed for e.g. deliveries during certain timeslots (that could be the times under the bicycle sign, but it's hard to read). I've worked in this area when it was under construction and in that time it was also already bicycle only. Google Maps also shows it as such.

The no-stopping sign indeed is odd if it was bicycle only, as afaik this sign doesn't apply to cyclists. There is also a separate sign indiciating this is a no-parking zone for cyclists (this is the station area, where it is common to only allow bicycle parking in designated areas, such as one of the biggest bicycle parking garages a bit further down this path and then to the left).

The lack of bollards is not odd. This is a common trend seen in other Dutch cities. E.g. Amsterdam has also removed a lot. It makes it safer for cyclists and generally car drivers are welbehaved enough to not use the bicycle paths.

Anyway, definitely not a car street. It's definitely a bicycle path with maybe some exceptions for cars. Curious to know if someone can take a look at that sign, I unfortunately do not visit Utrecht regularly anymore.