I noticed that terran scvs do different things on different geysers and sometimes go behind the gas, after some research I have come up with the following:

top right gasses need depots 1 hex above the gas to work properly
top left gasses don't bug even without depots behind
bottom left gasses work with depots directly behind them
bottom right gasses don't bug

Hope this helps, lemme know if anyone disagrees, maybe i'll add a picture if it helps.

Note: When I say "top right" i am referring to the geyser that is closest to the top right corner of the game field, and when I say "bottom left" I am referring to the geyser that is closest to bottom left of the game field, this explains why not every base has the same feel because those gasses are not always the 'inner' geysers in every base.