I don't think it's as easy as you're suggesting. GPS L1 jamming has been done routinely enough but the satellite bands (X/Ku/Ka) appear to be much more difficult to pull off.

Iran was reported to have mobile units with a fairly short range that constantly roamed around, only hitting 2 of the 3 bands (Ku/Ka). They're also reported to have received mobile Russian military units capable of jamming all 3 (X/Ku/Ka) over a much wider area. (I'm not actually clear the extent to which X band is associated with either Starlink or Starshield. Starshield also reportedly operates to at least some extent in parts of the S band. [0])

So the technology clearly exists but it doesn't seem to be something you can trivially throw together in your basement. That's quite unlike (for example) a cell phone jammer which a hobbyist can cheaply and easily assemble at home. I assume the extreme directional specificity of the antennas plays a large part in that.

[0] https://www.npr.org/2025/10/17/nx-s1-5575254/spacex-starshie...