It looks like
To much oil in the primary because the breather mod
was not finished ,... or perhaps , not done correctly
You should-not have that level of oil with either... the original sealed primary
The modified to 1970s " open primary " style .
Open primary uses no main seal and small drain back holes ... to control oil level over chain .
And then a baffled-hose out the top of the primary.
The factory also eliminated the hollow cam timed breather .
Your bike may or may not be running its original cammed breather ... or a breather thats plugged as part of the incomplete mod.
If you go back to a sealed primary , make sure the timed breather is there , and not plugged.
If running and open primary ... this is often plugged.
Original old style breather tube is shown here ( this tube is also know to oil much more than the chain )
... so is another source of leaks in this area .
Below is a pic of a later T100 factory open primary set up .
Note the small drain back holes locations , looks similar to yours
And the black sheet metal baffle ... for the breather hose .
If you add a breather to the oil filler plug , one of your simpler options ...it may not work as cleanly as the factory baffle ,
You may have to experiment with how large a hose and how vertical it runs ... to control oil mist .