Sounds like a mild case of bronchitis. Every time I get that it sounds and feels like my lungs are bubbling. It's just air moving past phlegm. It usually presents with other cold like symptoms like cough, sore throat, fever and runny nose, but I've had cases where the only symptom was the gurgling feeling. Most cases where people are reporting that feeling in their lungs it's actually their bronchial tubes, slightly higher up in the tract but an easy mistake to make.
But I recommend you see a doctor and have it checked out. You may need an inhaler or antibiotics. And if it actually is in the lungs it's always best to get that looked at regardless. Oh and I used to get bronchitis bad at least 3 times a year as a smoker and it would last weeks. That's one of the reasons I switched is because I felt like I was sick most of the time.
I got my first case of it just a few weeks ago since switching to vaping 2 years ago, it felt the same as before, but resolved in 3 days instead of 3 weeks.
I'll make that trade any day.