At "Attack rolls" on page 446 of CRB I could not find anything.
For generic weapon attack rolls, is there a difference between Failures and Critical Failures?
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Per PHB p10,
Similarly, failing the check by 10 or more is a critical failure (sometimes called a fumble). This sometimes results in additional negative effects. [...] Note that not all checks have a special effect on a critical success or critical failure and such results should be treated just like an ordinary success or failure instead.
Because, as you noted, there is no Critical Failure entry for Strike Actions, there is no additional penalty without some other ability being in use.
The Fighter Feat Dueling Riposte is an example of a situation that changes this.
Trigger A creature within your reach critically fails a Strike against you.
There are also abilities baked into some Bestiary creatures (however they seem generally rare at the time of this writing). The Gimmerling (Bestiary p177) is one such example.
Trip Up [reaction] Trigger A creature critically fails a melee attack to hit the gimmerling or moves into a space within the gimmerling’s treacherous aura.