Is this a healthy way of eating?

it doesn't matter when you eat your calories

but, please check that you goals and targets are themselves healthy, 1200-1300 calories is very low
if you got there by selecting a 2lb/week weightloss goal, my advice would be to change it to 1lb or 0.5lb as this is a more sustainable loss rate which makes it more achievable and less likely to cause binge and weight cycling

good luck with your weighloss journey

Intermittent fasting can work very well for some people... nothing unhealthy about it, so long as you're getting a healthy amount of calories overall, and not going too long without food (16-24hr fasts are usually fine unless there's a medical reason why not - but I wouldn't advise fasting longer than this)

1200-1300 cals/day is not enough for most people.... make sure your daily average number of calories is the right amount for healthy fat loss. IF isn't a short cut for faster fat loss and it isn't going to magically make you lose more fat; it's a way of timing meals that helps some people stick to the right amount of calories for them and avoid overeating. Meal timing doesn't affect fat loss... but it can have a great impact on compliance. Some people find it easiest to stick to a calorie deficit if they have several small meals a day, others find it easier if they do IF and have one large meal or one eating window (i.e. 8 hrs during which time they eat and the rest of the 24 hrs they don't eat) - so choose whatever is going to work for you in terms of sticking to a calorie deficit.

a more sustainable loss rate which makes it more achievable and less likely to cause binge and weight cycling

I don't agree that how fast you lose weight effects how well you will keep it off. [...] It's a myth people tell themselves when they go back to their old ways of eating and want to blame the weight gain on something else.

I didn't say that - I mentioned that people who target very low calorie intakes are more likely to binge and yoyo cycle, i think this is due to a lack of adequate nutrition and feeling hungry, and while it is possible to feel full on 1200 calories it takes a lot of effort

also I believe (rightly or wrongly) that for me, weight gain was about a failure to make accurate decision about portion size, losing weight slowly and sustainably without supplements, cutting out food groups allows me to re-learn appropriate protion control and learn better habits, so I think that losing slowly and sustainably allows one to better avoid "going back to old ways" as you put it, because the slower progress has enabled new habits to be developed which are healthier, and i'm a firm believer that habits (good or bad) are harder to break than intentions no matter how strongly held or well intended

I've heard intermittent fasting works for some people, but to be honest I'm not totally sure HOW that'd work.

Think about what you just wrote. Eat nothing for 14-16 hours, then eat 1200-1300 calories all at once, then not eat anything again until the next day. For starters, I'm not sure how you'd healthily consume 1200-1300 calories at once. I had a huge burger and fries last night for a cheat meal and that was "only" 1100cal. I felt like my stomach was about to explode, and that's pretty caloric-dense food! I couldn't even begin to imagine trying to consume 1200cal of fruit or vegetables and lean meats in one sitting...

Just curious, why the intermittent fasting? If I ate all at once then didn't eat for a while, I'd feel dizzy due to blood sugar fluctuations. If it works, it works... but I don't see the point in shoving in a day's worth of calories for your body to process all at once.