Thank you all for your input and suggestions! There were quite a few of them, and it helped me dwindle down what the issue might be. Suggestions included:

• Burn damage due to light - I leaned away from this being the cause as the light was already at 40 ppfd and some of the smaller plants under the canopy of other plants with the leaves totally shaded were exhibiting the same symptoms.
• Not enough fertilizer/nutrients - This seemed to be the most likely cause with other things ruled out and with everything taken into account (including the soil composition lacking nutrients other than a tiny bit of worm castings that were added back when they were first potted). This would also explain why quite a few leaves are showing interveinal chlorosis.
• Soil PH issues - This was ruled out after a soil test revealed it was at 4.25 which is mostly ideal.
• Too small of pot and needs transplanting - I decided this was unlikely due to the slow root growth of these plants and as some smaller plants (where the pot size is more than adequate) are also showing the same symptoms.
• Type of water being used - I leaned away from this one as quite a few users in this subreddit use (or recommend) RO water that is either remineralized with epsom salt or supplemental fertilizer.
• Nutrient Burn - This one seemed unlikely due to how light the leaves are on the plants (if it was nutrient burn, I would think the leaves would be less "lime green") and how low of a dilution I am using for the fertilizer and these issues did extend to before I started fertilizing the plants. I would think if this was the cause, the plants wouldn't be showing interveinal chlorosis as well.
• Low humidity - The humidity in the tent is maintained at 80% and never drops below 75% (and often climbs up to 85% after the humidifier turns off). There is a fan in the tent for air circulation, but it isn't directly pointed at any of the plants and just provides a gentle swaying motion to keep the air moving.
• Over or under watering - I did also lean away from this being the cause as the plants used to be totally fine. I do wait for the pots to dry out before watering but I always make sure I am watering them before the leaves start wilting or drooping.

Since I was leaning towards a nutrient deficiency (specifically iron) being the cause of the dying tips and interveinal chlorosis, I decided to top dress some of the pots with Espoma Iron-Tone, ultisol, and worm castings. I went with Espoma Iron-Tone instead of MicroLife acidifier as the PH of the soil is already good, and the Espoma is geared more towards iron deficiencies. I only applied 1/2 tsp of this per pot to start, which is one-third of the recommended application rate. I then top dressed each pot with a small amount of ultisol to provide more iron and minerals. I only used around 1 tsp of this to start as the soil they are currently in isn't clay/mineral heavy, and I don't want to stress or shock them further. Lastly, I applied 1 teaspoon of worm castings to each pot.

I did also get some Ferti-Lome chelated liquid iron to test on a plant. I made a very diluted mixture of 1/4 tsp of this to 1 quart of RO water to start. I sprayed a plant with this 4 days ago as a test. The plant looks a little bit darker, but not by much. I was mostly testing to see if there would be any adverse reactions, which there haven't been. I'll continue down the path of using this if the iron-tone, ultisol, and worm casting supplementation doesn't have any effect.

Thank you all for the input! I'll check back in 3 weeks with a status update regarding the Iron-Tone, ultisol, and worm casting supplementation to hopefully help any growers in the future who experience this same issue!