I see that some people are trying the 1.21 minecraft snapshot - but how can I install it? I do not see any 1.21 option when looking for installations and the snapshots 23w43a or 23w44a seem to be something else (as they do not have the copper bulb). What am I missing here?
23w43a and 23w44a are snapshots for 1.20.3. There currently are no snapshots for the actual 1.21 version.
1.21 features (such as the Copper Bulb) can be accessed in these versions by enabling the 1.21 experiment in the Create World menu, which can be found in
Create New World > More > Experiments. Do note that you will need to create a new world to do this.