Yes - quite scarce. What's interesting abut this star-over-altar issue is that we see Daia both as caesar (GENIO CAESARIS) and as augustus (GENIO IMPERATORIS) in the same issue. The IMPERATORIS type is a lot more common.
Here is my only halfway decent Maximinus II Daia: Maximinus II Daia Æ Follis (305-306 A.D.) Heraclea Mint GAL VAL MAXIMINVS NOB CAES, laureate head right / GENIO POPV-L-I ROMANI, Genius standing left in chlamys holding patera and cornucopiae, HTΓ in exergue. RIC VI Heraclea 26b. (10.92 grams / 26 x 25 mm) eBay Jan. 2020 This one from the same era just came in a couple days ago - Constantius I Chlorus, another GENIO POP: Constantius I Chlorus Æ Follis (struck by Maximian) (294 A.D.) Siscia Mint FL VAL CONSTANTIVS NOB C, laureate head right / GENIO POP-VLI ROMANI, Genius standing left, holding patera and cornucopiae, S in left field, Γ in right field RIC VI Siscia 81a. (8.53 grams / 26 x 25 mm) eBay Aug. 2021