Uh, wut? If you placed a level in the middle of a playfield and the bubble was in the middle that would mean your playfield was LEVEL, with no slope, and the ball would never trend towards the flippers or the apron.

I'd suspect the playfield might be sitting out of position slightly. Caught on a bundle of cables in the back maybe?

Other possibilities: legs not the same length? Built-in level not installed properly?

Compare the position of the bubble on your level in the middle of the pf to other games, see if it's close.

https://www.amazon.com/Protractor-Inclinometer-Measuring-Carpentry-Automobile/dp/B07R12DZQ9

I use this cheap digital level- works great and it’s $15.99

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I'll play along.
The yellow level you show is for leveling things such as construction and it is set-up to be accurately for that purpose.
The level built into the pinball machine that not many of us go by is set-up so that it shows in the middle(roughly) when the machine is in the right area.
But what you should be using is a angle finder gauge, at minimum get one from harbor freight.
Find the sweet spot for the machine and the way you like it.
Most of us are between 6.5 and 7 degrees.

-Mike

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