Thanks for the additional data. Here is what I see in that data:
Usage detected by your main is 1,6387.7 kWh per the app (rounded to 1640 kWh in the monthly report) over the month of August which has 31 days at 24 hours per day, thus average usage = 2,202 watts. Analysis matches the monthly report, ✓
Usage expected to be seen by the DCM should be the value listed as From grid minus the value listed as To grid. Let’s see: 1,149.6 kWh minus 195.8 kWh = 953.8 kWh (listed as negative 954.2 kWh under net solar production). If this is again divided over the number of hours in August, the DCM should be seeing an average of 1,292 watts. Instead it reports 288 watts, which is the discrepancy you note.
Regarding the percentage of solar production, 42% is listed next to net solar production. This is the value I would expect if dividing your total solar production by your total usage. The difference between 42% and 30% was discussed in a thread several years back, where a user called one net and the other coincident solar.
Finally, I noticed that the ratio of To grid energy to From grid energy was 17% while the ratio of To grid cost to From grid cost was 13%. That discrepancy probably just means that the time-of-use feature is working as intended for your household.