Turned Capital F

It marked V’s consonant use separately from its vowel use.

During Emperor Claudius’s reign, 41–54 CE, this Claudian letter was proposed as one of three additions to Latin spelling. Latin V could stand for both a consonant and a vowel; Ⅎ marked the consonant use, leaving V available for the vowel. The proposal did not become everyday Latin spelling.

Where does the name digamma inversum come from?

It points to Greek digamma, but the letters are distinct.

The Latin name invokes Greek digamma Ϝ as a model or name reference. Ⅎ was a Latin reform letter, not another spelling of the Greek character; the same proposal included Ⱶ and Ↄ.

In scholarly editions of ancient Latin inscriptions, editors may preserve Ⅎ to show the historical letter or normalize it to V. Normalizing makes the text easier to read in familiar Latin spelling, but it hides which sign the inscription used.

Is Ⅎ just a mirrored F?

No. It is turned, not mirrored.

Turned means rotated 180 degrees; ꟻ is a separate Latin character mirrored across a vertical axis. Fonts may draw Ⅎ differently, but changing the font does not change which character the text contains.