The spec's list the magimum SD card capacity as 128GB IS this a file system limitation? or a transfer speed limitation?

People online claim to have run them with bigger cards but are there any limitations or side effects of doing so?

Use whatever size card you like, right up to the size corresponding with how much of your work you are prepared to lose all at once.

There is a wisdom that says 'Don't use a card any larger than you could bear to lose with the aircraft.' In other words, it is probably wise to use cards of around 32GB or so and have a number of them on hand, because you would be pretty pi$$ed off if you lost the aircraft with 128 GB of photos or video on it. If I am shooting a subject and it requires more than one battery to complkete the mission, I always change card when I change battery.

As for transfer speed, the read speed is irrelevant, the most important speed is the maximum sustained record speed. For this reason, I do not buy cheap cards, I always buy Sandisk EXtreme Pro cards, then you know you have one that is fast enough.

Hello there Gidge. Thank you for reaching out and for these information you have posted. DJI suggest using a suggested SD card on your DJI Drone for compatibility and reliability purposes. In addition, the maximum capacity of a single file will not exceed 4GB. If exceeded, the recording will be stopped, and a new recording will be started. In addition, the maximum file size of FAT32 is 4GB. Hence, a file that is larger than or equal to 4GB will be divided, otherwise, the file may be lost or abnormal and cannot be read. Although exFAT allows a larger file size, the larger file may be damaged due to abnormal power-off and SD card removal, or even cannot be recovered. So the storage of the camera is 4GB regardless of the file systems. So it is normal the video will be split if it reaches 4GB. Thank you and fly safe always.

DJI Stephen Posted at 11-26 21:06
Hello there Gidge. Thank you for reaching out and for these information you have posted. DJI suggest using a suggested SD card on your DJI Drone for compatibility and reliability purposes. In addition, the maximum capacity of a single file will not exceed 4GB. If exceeded, the recording will be stopped, and a new recording will be started. In addition, the maximum file size of FAT32 is 4GB. Hence, a file that is larger than or equal to 4GB will be divided, otherwise, the file may be lost or abnormal and cannot be read. Although exFAT allows a larger file size, the larger file may be damaged due to abnormal power-off and SD card removal, or even cannot be recovered. So the storage of the camera is 4GB regardless of the file systems. So it is normal the video will be split if it reaches 4GB. Thank you and fly safe always.

I think you misread the question Stephen.

He was not asking about the max file size of a single file but the max card size that can be fitted in the drone.

DJI Stephen Posted at 11-26 21:06
Hello there Gidge. Thank you for reaching out and for these information you have posted. DJI suggest using a suggested SD card on your DJI Drone for compatibility and reliability purposes. In addition, the maximum capacity of a single file will not exceed 4GB. If exceeded, the recording will be stopped, and a new recording will be started. In addition, the maximum file size of FAT32 is 4GB. Hence, a file that is larger than or equal to 4GB will be divided, otherwise, the file may be lost or abnormal and cannot be read. Although exFAT allows a larger file size, the larger file may be damaged due to abnormal power-off and SD card removal, or even cannot be recovered. So the storage of the camera is 4GB regardless of the file systems. So it is normal the video will be split if it reaches 4GB. Thank you and fly safe always.

Thankyou Stephen. I understand the limitations of FAT32 and exFAT. My question was more about compatibility with larger micro SD cards.

The Mavic 2 Pro's specification sais it's compatible with cards "UP TO 128gb" My question is will it run with a larger capacity cards and what, if any are the issues with doing so?

I would agree with the others, no way would I use a 128 or larger just because I would never want to lose that much content all at once if something went awry.  Buy multiple smaller cards and swap them out more frequently!