Part 107 UAS pilot reported that while conducting a photo flight they had a near miss with an aircraft landing at a nearby private airport. The UAS pilot checked LAANC apps prior to flight but the privately owned airport was not depicted.

Narrative

I was flying my drone for real estate photography [at] Location A; taking video and pictures of neighborhood amenities. Before I started somewhere 1 hour before the mission I opened Aloft app as usual to check for airspace and if I need to request LAANC. The app said it is not applicable to the airspace of intended flight. Then I checked the weather and condition was fine; so I arrived at Location A [in] McKinney; TX and started flying my drone about 100 ft AGL. Then I decided to climb up to 300 ft AGL to take a photo of wide area when all a sudden an aircraft was flying base to final. It is hard to say how high that aircraft was from my drone and how far laterally but it was not safe. Luckily there was no collision and nobody was injured and nothing was damaged. I descended my drone asap (it was in 'tripod' mode) and terminated UAS operation. There were no restrictions on the Aloft app; and not even cautions; however I still believe that I violated something. At least I put too much trust on the app and this led me to complacency that my operation will not interfere with any other flight operations.After I came home [I] started researching and found out there was the T31 airport depicted on Skyvector.com. I visited the airport website and there was a section where they posted rules for flying drones near their airport. I am not in violation of any of those rules listed there; except they wanted all drone operators who intended to operate a drone within 5 miles of their airport submit a request via email. I was really discouraged. I wish to contribute to safety a little and ask you guys if you have any influence on such apps like Aloft or B4UFLY; please update them to highlight private airports on the map within apps and if there are no LAANC [requirements] it will be good to see at least caution markings over such airports. Something like 'Caution Required Here! Visit airport website or contact airport administration to comply with their regulations'.During my operation there was another person who was flying a drone approximately 300 ft AGL; his battery died and he left earlier; but [I] talked with him about drones. I believe he was a local; but he did not tell me anything about T31 airport and their regulations; therefore I believe that person was not aware as well.