I am a veggie, been so for many years. I also was vegan for a while but went back to lacto-ovo veggie. To me true-blue strict veganism just isn't sustainable or reasonable for most people today, and I found the vegan ideology of absolute extreme prohibition to actually be very damaging (there is alot of martyrdom, guilt tripping, and shaming that can occur in the vegan community - tons of pressure and feeling "not good enough"). Vegetarianism on the other hand tends to be far more flexible.
Vegetarianism has many health benefits but it should be noted that most of its benefits can absolutely be found in an omni diet as well. Veggie strengths are increased intake of fruits and veggies, and no intake of the processed meats that have been associated with certain health conditions. Notice how both of these things are not necessarily vegetarian-specific behaviors - plenty of omni people eat loads of fresh produce and avoid red or processed meats. Beware of veggie propaganda that likes to spin these behaviors into an argument for vegetarianism - as if omni eaters can't do the same things.
Downsides of vegetarianism are limited choices/flexibility in ones eating pattern, and if vegan, abnormally low levels of fat and b vitamin intake. If you are going to go all in and be mostly vegan, you really have to know what you are doing from a nutritional standpoint, take supplements, and make a concerted effort to eat lots of higher fat plant foods like avocados, olive oil, and nuts on a daily basis. Many people harp on the protein, but I found it much easier to get protein than fat in a vegan diet. Lacto-ovo vegetarians generally do not have this issue as they get alot of fat from egg and dairy. Also important to know is that sometimes the act of getting too into veggieness can be harmful for mental health - a disproportionate number of people who go veggie have mental health issues or histories of disordered eating patterns. If you already struggle with black and white thinking, self esteem, or have a history of eating issues, think carefully before committing to a diet that requires you to constantly be enforcing restrictions and measuring yourself against a benchmark of what "good" eating is. Vegetarianism won't cause these things, but being strongly drawn to the black and white restrictions of certain dietary lifestyles can be indicative of unhealthy thinking patterns. For these people, constantly living life by strict rules of what they should and shouldn't eat might be far more damaging than adopting a more flexible eating arrangement.
Based on my health background, I am not an advocate for any one style of eating, but rather think people should eat a whole foods diet with low/limited processed foods and low sugar. Refined carbs and sugar are the worst health offenders, but avoiding processed meats except as a treat is probably also important. After that though, it really is all about how you feel on your given diet. Vegetarianism can be great but only if you feel good and enjoy it - if you do not, then it isn't the right path for you. No one dietary ideology is right for everyone, so experiment and be flexible. It is totally okay to bounce around or change your mind. You can be mostly vegetarian (reductionist or flexitarian), pescetarian (only fish), any number of vegetarian (lacto only, lacto ovo, ovo only), vegan, etc. No one is "better" than the other for a given individual.